Wireless duplex signaling system.



L. ES PENSCHIED. WIRELESS DUPLEX SIGNALING SYSTEM.

' APPLICATlON HLED MAY l5| l9l6- 1,25 9, Patented Feb. 19,1918.

3 SHEETS-SHEET Inventor LE3 enschi a p67 w L. ESPENSCHIED.

WIRELESS. DUPLEX SIGNALING SYSTEM.

APPLICATION FILED MAY 15. ms.

1,256,889. I Patented Feb. 19, 1918.

SSHEETS-SHEET 2- L, Elnbnior s 6l78C/7/Z'd pep Jttorney.

L. ESPENSCHIED.

WIRELESS DUPLEX SIGNALING SYSTEM.

APPLICATION FILED MAY 15 I916.

Patented Fb. 19,1918.

3 SHEETS-SHEET 3.

lull- Hill'- Z. Espenschied per aft turnkey.

UNITED STATES PATENT OFFICE.

LLOYD ESPI ZNSCHIED, 0F HOLLIS; NEW YORK, ASSIGNOLR '20 AMERICAN TELHHQHE ND TELEGRAPH COMPANY, A CORPORATION OE NEW WIRELESS DUPLEX SIGNALING sYs'rEM.

Specification of Letters Patent.

Patented Feb. 19, 1,918..

Application filed May 15, 19-16. Serial No. 91,565.

To all whom it may concern Be it known that I, LLOYD Esrnnscrrrno, residing at Hollis, Long Island, in the county'of Queens and State of New'York, have invented certain Improvements in Wireless Duplex Signaling Systems, of which the following is a specification.

This invention relates to a wireless signaling system and more particularly to a Wire less duplex signaling system. Its object to provide a system for the simultanomis transmission and reception of signals and in particular to provide means for duplex communication between two stations.

For successful duplex operation it is no; essary that the receiving arrangements be effectively protected from interference by the transmitting arrangements at the same station that is, protected from whatis known as side tone. It is well known that in wireless telegraph and telephone systems the magnitude of the transmission current "is enormously greater than that excited in theantenna by the received waves, the relative magnitude of the former with respect to the latter being of the order of one million to one. This enormous ratio renders inapplicable to wireless systems methods of transmission interference elimination which are successfully employed in ordinary wire telegraph and telephone systems. The wireless system is, however, differentiated in two important respects from the ordinary wire system; first, signals are transmitted on high frequency carrier waves of definite frequencies, this fact permitting of the employment of different frequencies for trans mission and reception, and, secondly, resonant tuned circuits may be employed,- thus rendering the receiving system selective with respect to the waves it is desired to receive.

In my present invention 1 provide for successful duplex operation by employing carrier waves of different frequency for transmission and reception and by neutral izing the inductive action of the transmitting system iproper on the receiving system by means 0 balancing circuits. 4

My nvention is best understood by reference to the accompanying drawmgs 1n which- Figures '1, 2-, 3 and 4: is each a die gram of a system embodying the Invention.

Referningto Fig. 1, lie minimum for ,the simul n ous tvananisaim and reception of signals. Antenna 1 includes two parallel branchesQ and 3, transmitting circuit 4 beingcoupled to branch 2, while the receiving arrangements are coupled to branch 3. By

virtue of said parallel branches, the antenna 1 system has two degrees of freedom and is therefore resonantly responsive to two different frequencies. It. ,is contemp ated. that signals be transmitted at one of Said. frequencies and received at the other of said frequencies. The transmitting arrangement proper is conventionally represented 83. a high frequency generator 5, which generates waves of the frequency of transmission, in translating device 35 being provided t9 control the transmission of oscillations, De

3 must therefore balance at the transmitter frequency both as regards magnitude and phase of currentin-th-eir effects on, circuit 6. The balance as regards magnitude may be controlled by adjustment of the couplings between circuits 7 and 4e and circuits"? and 6' while by adjustment of condensers 8 and 8' the phase of the current in circuit .7 may be controlled. proper adjustments of-the above-mentioned circuit variables, circuit 6 may be be ten-- dered tpproxlmately free from-,interferencc r due to transmissioncurrents, v

As .re ards the receptionjof waves which it is desired to receive and-to which oscillation circuit 6 is tuned, itis clear that the bnlancingact-ion of branch 3 and circuit-1' with respect to circuitB nolongerob't'ainssince said balance-is adjusted only for the frequency of transmissionand-since.also, as regards'the received-m nes, antenna 1- isithg It is then clear that by driving circuit. Oscillation circuitiqlthew fore oscillates, r antly in, r sp us'eto the waves rece ved from the ,drstantcommumeating stanon and receiver 9}; thereby enermead ' which are both preferably of'the vacuum tube type. m

Referring to Fi 2 the arrangement shown is similar to that illustrated in Fig. 1, differing only in the balancing circuit arrangement. Coup] d to circuit 4 is a circuit 12 to whichis con ected the input side of a. vacuum tube' amplifier 13. The output circuit 14 of said amplifier is coupled to circuit 6. The operation of this arrangement in balancing the transmission interference in receiving circuit 6 is similar to that of the arrangement of Fig. 1, the arrangement of Fig. 2 being more flexible in that the rnagni-- tude of the balancing current in circuit .11 may be controlled by amplifier 10, thus permitting of nicer balancing adjustments. Ad-

ustment of phase relations .may be obtained y varying the capacity of condensers 15 and 1 Fig. 3 is a diagram of a wireless telephone system for the simultaneous transmission and reception of speech signals in which. separate antennae are employed for the transmlssion and reception. Referring to said figure, 21 is the transmitting antenna and 22 the receiving antenna. Antenna 21 is tuned to the frequency of transmission, that is to the frequency of the carrier wave generated by high frequency generator 23, while antenna '22 is tuned to the frequency of the signals to be received, that is to the recepti'on frequency. The transmitting system proper comprises the generator 23, a modulating device 24, preferably of the vacuum tube type and an amplifier 25 whose output circuit 26 is coupled to antenna 21. Telephonic waves generated by transmitter 27 are transmitted by line 28 to modulator 24s in which they are combined with the carrier wave generated by generator 23 to produce modulated high frequency waves.

Line 28 is also coupled to antenna 21 and is therefore excited by the high frequency waves in said antenna and transmits high frequency current to the receiving antenna.

' station as well as audio-frequency current to the transmitter. High frequency Waves of similar form are also radiated from antenna 21 and excite oscillations in antenna 22 which interfere with the reception of the -'-desired signals. In the present organization I con-template balancing in their effects on receiving oscillation circuit 29 the high frequency waves transmitted by wire line 28 and those transmitted wirelessly to antenna 22. As shown both line 28 and antenna 22 are coupled to oscillation circuit 29 and by a proper adjustment of relative couplings and of condensers 33 and 33 the resultant induction in circuit 28 may be substantially 'eliminated as regards the effects originating at the transmitting station. Oscillation circult 29 is --further protected against transmissionv interference by being tuned to thefrequency of receptionand oitering a relatively high impedance to the frequency of transmission.

As regards the reception of signals antenna. 22 is strongly responsive while an tenna 21 is weakly responsive. The balance between the inductive eliects of line 28 and antenna 22 on circuit does not therefore obtain as regards the signals to be reccived. Further oscillation cuit 29 is resonantly responsive to said Si ids, and receiver 30 connected to said circuit through detector 31 and ampiilier responds to said signals. 7

Fig. 4 is a. diagram illustrating an arrangcmcnt which is similar in general to that sho'wnin Fig. 3. Corresponding com ponent parts of Figs. 3 and t are designated by the same numerals. Referring to Fig. 4. transmitting station A and receiving station B are connected by wire line 28. Generator and modulator E24 are located at receiving station B; modulated high frequency waves are transmitted by line to transmitting station it where they are amplified by ampli 25 and then radiated by antenna 21.

Line 28 is coupled to receiving oscillation circuit whi h is also coupled to receiving antenna 22. a. proper adjustment of coupling, and of phase by means or" condenser 34, interference, as regards transmitted eil'ects may be eiiminated from circuit 29, leaving it free to oscillate resonantly to the waves it is desired to receive.

hat is claimed is:

1. In a system for the simultaneous transmission and reception. of signals, a circuit tuned to one frequency for transmission, a circuit tuned to another frequency for reception, a. transmitting apparatus, means for ociating the same with said first sir cuit a. receiving apparatus, means for asso- (dating the same with said second circuit, haiancing circuit and means for coupling balancing circuit to the means for associating said transmitting and receiving apparatus with the tuned circuit so as to render said receiving apparatus free from in terference by the transmitted energy.

In a system for the simultaneous transmission and reception of signals, a circuit tuned to one frequency for transmission, a circuit tuned to another frequency for reception, a transmitting apparatus, a. circuit for connecting .the same with said first tuned circuit, a receiving apparatus, a circuit for connecting'the same with said second tuned circuit, and means to neutralize the effect of transmitted energy upon the receiving apparatus, said means being connected to said connecting circuits and through said connecting circuits with said tuned circuits.

3. In asystem for the simultaneous transmission and reception of signals, an element tuned to transmission frequency, a second element tunedjto reception trequency, a

transmitt'ing apparatus,

mission and reception of signals, an element tuned to transmission frequency, a second element tuned to reception frequency, a

a circuit for coupling theisame to the first element, a receiv ing apparatus-,- a circuit for coupling the same to the second element, and an auxiliary circuit connectin "the coupling circuits, said auxiliary circuit sing provided with means includingan amplifier to OYGICDIIHE t effect of transmitted energy upon the recei. paratus'.

"In a system for simultanem mission and reception of simals, an ant circuit provided with, two patina a trace mitting apparatus associated w said first path, a receiving apparatus'associated with said second path, and an'auxiliary circuit coupling the transmitting and recelving apparatus, said auxiliary circuit being proyided with means to overcome the effect of transmitted energy upon the receiving apparatus.

6. Inc system for the simultaneous transmission and reception of signals, an antenna circuit provided with two paths, a trans mittingrapparatus associated. with said first path, a receiving apparatus associated. with .said second path, and an auxiliary circuit coupling the transmitting and receiving apparatus, said auxiliary circuit heing provided with means including an amplifier to overcome the effect of transmitted energy "upon the receiving apparatus.

7. In a system for the simultaneous-transmission and. reception of signals, a circuit tuned to transmission frequency, a circuit tuned to reception frequency, a transmitting apparatus, means for connecting the same with said first circuit, a receiving apparatus.

means for connecting the same with said second circuit, and an auxiliary circuit coupled to said connecting means and connected through said connecting means to said tuned circuits, said auxiliary circuit comprisin means to overcome 'the effect of transmitted energy upon the receiving apparatus.

8. In a system for the simultaneous transmission and reception of signals at different frequencies the combination of an antenna system reasonantly responsive to two frequencies, a transmitting circuit arrangement coupled to one element oftsaid antenna s stem, a receiving circuit arrangement coup ed to another element of said antenna system and a balancing circuit coupled to both said transmitting circuit arrangement and 'said receiving circuit arrangement, and means included in said balancing circuit whereby the receiving circuit arrangement is substantially free from interference by the transmitted energy.

9. In a Wirelesssystem for the simulta .neous transmission and reception of signals at different frequencies the combination of so system resonantly responsive to the frequency of transmission and the fre- @{dtllltjv reception; a transmitting circuit, arrangement coupled to one element of said antenna system; a receiving circuit arrangement coupled to another element of said antenna system; a balancing circuit coupled to both said transmitting circuit arrangement and said. receiving circuit arrangement; an amplifier in said balancing circuit and means for controlling the phase ofthe circuit in said balancing circuit.

10. A Wireless signaling system for the simultaneous transmission and reception of signals comprising an antenna including two parallel branches, said antenna'being resonantly responsive to two frequencies; a transmitting arrangement coupled to one of said branches; a receiving arrangement coupled ,to the other of said branches; a

balancing circuit coupled to-said transmitting arrangement and said receiving arrangemcnt; and means included in said balancing circuit for neutralizing as regards phase and magnitude the transmission interference in said receiving arrangement.

In testimony whereof, I havesigned my name to this specification in the presence I of two subscribing witnesses, this 4th day of May, 1916.

LLOYD. ESPENSCHIED. Witnesses: v

RALPH W. WoLr,- FREDK S. Ronnvsom. 

